Glow plug



GLOW PLUG Filed Aug. 26, 1968 INVENTOR Karl WOLF a 4 y v fi'kar hisATTORNEY United States Patent Int. Cl. Fis 7/06 US. Cl. 431-263 6 ClaimsABSTRACT OF THE DISCLOSURE A glow plug for use in diesel enginescomprises a housing having an internal passage provided with a frontend. An elongated glow pin is rigidly mounted in this passage definingwith the inner circumferential surface thereof an annular fluid conduitthrough which fluid may flow towards the front end of the passage. Theglow pin has a free end located adjacent the front end. An annular sieveinsert is mounted in the conduit concentrically surrounding the glow pinin the region of the free end thereof with spacing both from the glowpin and the inner circumferential surface and thus defines an inner anda concentric outer annular clearance with the two, only the outerannular clearance directly communicating with the fluid conduit so thatfluid from the latter must pass through the outer annular clearance andthrough the sieve insert in order to reach the inner annular clearance.

BACKGROUND OF THE INVENTION The present invention relates generally toignition devices, and more specifically to a glow plug.

Glow plugs are used in diesel engines for the purpose of igniting acombustible fluid supplied to them in order to in turn heat theaspirated combustible mixture which energizes the diesel engine. Glowplugs of this type are used to aid in start-up of diesel engines and inafterburning or afterignition at higher revolutions.

Such glow plugs must insure a droplet-free combustion of the combustiblefluid, that is the fluid must be vaporized. To assure this the glow pinutilized in such glow plugs is surrounded by or extends into a mixingchamber whose efliciency may be enhanced by provision of a sieve-typeinsert. Thus, it is known in one prior-art type of glow plug to havesuch a sieve-type insert located in and filling a portion of the mixingchamber which is provided at the operative end of the glow plug, that isthe end thereof at which ignition occurs. However, this construction hasnot been found satisfactory because the ignition speed and thevaporizable quantity of combustible fluid are inadequate.

It is thus an object of the present invention to overcome theseaforementioned disadvantages.

More particularly, it is an object of the present invention to providean improved glow plug which is not subject to the disadvantages setforth above with respect to the prior art.

SUMMARY OF THE INVENTION In pursuance of the above objects, and otherswhich will become apparent hereafter, one feature of my inventionresides in the provision of a glow plug which is particularly suited foruse in diesel engines, and which includes the housing provided with aninternal passage having a front end, this passage being bounded by aninner circumferential surface. An elongated glow pin is received in thepassage rigid with the housing and defines with the innercircumferential surface of the passage an annular fluid conduit throughwhich a fluid may flow in direction towards the front end of thepassage. The glow pin has a 3,529,914 Patented Sept. 22, 1970 free endlocated adjacent the front end of the passage. An annular sieve insertis mounted in the conduit and concentrically surrounds the glow pin inthe region of the free end thereof. It is spaced both from the glow pinand the inner circumferential surface bounding the passage and thusdefines an inner and a concentric outer annular clearance with the glowpin and with the inner circumferential surface, respectively.

By resorting to my present invention the problems outlined above withrespect to what is known in the field are overcome. The reason for thisis that the relatively large annular space between the glow plug and thesieve insert avoids the formation of carbon deposits resulting fromimproper combustion of fuel oil because the spacing which exists betweenthe sieve insert and the inner circumferential surface of the internalpassage, that is the concentric outer annular clearance mentionedbefore, provides protection against cooling of the sieve insert throughheat conduction towards the exterior of the glow plug. Moreover, mynovel glow plug construction assures that in the annular clearances ahighly satisfactory admixture of combustible fluid and air will takeplace.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its mode ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanyin g drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal sectionthrough a glow plug according to my present invention;

FIG. 2 is an end View of the downstream end of the glow plug shown inFIG. 1; and

FIG. 3 is a section taken on the line IIIIII of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing indetail I wish it first to be understood that glow plugs per se arealready well known in the art, and that I have therefore either omittedor illustrated only in diagrammatic form such details as are alreadyWell known from conventional glow plugs and do not form a part of myinvention.

'Referring now to FIG. 1 it will be seen that the glow plug comprises ahousing consisting of a first housing portion and a second housingportion 15. The portion 15 is also frequently identified as a protectivetube or designated with a similar term, but it will be evident that itmay be thought of as a part of the housing which thus consists of theportions 10 and 15 together. Received in the internal passage providedin the housing 10, 15 is a conventional glow pin 11 which in theillustrated embodiment is rigid with the housing portion 10. The glowpin 11 defines with the inner circumferential surface bounding theinternal passage provided in the housing and annular fluid conduit 10ainto which the combustible fluid enters in the direction indicated bythe arrow in FIG. 1 to flow through the conduit 10a in the directiontowards the front end of the internal passage.

As shown in FIG. 1, the free end or the free end portion 11a of the flowpin 11 is located inwardly of the open end of the housing portion 15,and is surrounded by a sieve-type insert 12. The latter is ofconventional construction, materials for such inserts being well knownin the art, and of annular cross-section as clearl visible in FIGS. 2and 3. By virtue of the fact that the annular seive-type insert 12 isspaced both from the inner circumferential surface bounding the internalpassage of the housing 10, 15 and from the free end portion 11a of theflow pin 11, it defines with the glow pin and with the innercircumferential surface an inner and a concentric outer annularclearance, the former being identified with reference numeral 118 andthe latter being identified with reference numeral 19.

In the illustrated embodiment the sieve-type insert 12 is centered onand with respect to the glow pin 11 by a ring member 13 whichadvantageously embraces and clamps the upstream end portion of theinsert 12 so as to prevent the same from coming apart, for example if itconsists of a strip of sieve material which is to be maintained inannular shape against its inherent tendency to assume a different shape.The ring member 13 is provided for this purpose with clamps 13a,although it will be appreciated that it could itself be of substantiallyU-shaped cross-section to embrace and clamp the upstream end portion ofthe insert 12 in the same manner as but in view of the clamps 13a. Otherpossibilities will of course readily suggest themselves to those skilledin the art.

As visible in FIG. 1 the ring member 13 serves another purpose, namelyto close the upstream end of the inner annular clearance 18 so thatfluid flowing through the conduit ia cannot enter directly into theclearance 18. Rather, such fluid will enter into the outer clearance 19whose upstream end is not similarly closed, and will be forced to passthrough the material of the sieve-type insert 12 in order to enter theinner annular clearance 18.

Reference numeral 17 designates the mixing chamber of the novel glowplug, which mixing chamber 17 is formed in the illustrated configurationand location as a result of the fact that, in accordance with a furtherfeature of the invention, the insert 12 extends axially forwardly andbeyond the end of the glow pin 11, and is fastened and centered by abridge 14 in the housing portion 15. This feature in fact greatlyenhances the efficiency of ignition and, in conjunction with theconcentric arrangement of the insert 12 about the end portion lla'of theglow pin 11 with clearance both from the latter and from the innercircumferential surface bounding the passage in the housing 10, '15,constitutes an important aspect of the present invention.

It will be understood that each of the elements described above, or twoor more together, may also find a internal passage having a front endand being bounded by an inner circumferential surface; an elongated glowpin received in said passage rigid with said housing and defining withsaid inner circumferential surface an annular fluid conduit throughwhich a fluid may flow in direction towards said front end, said glowpin having a free end located adjacent said front end of said passage;an annular sieve insert mounted in said conduit concentricallysurrounding said glow pin in the region of said free end thereof withspacing from said glow pin and said inner circumferential surface anddefining with the two an inner and a concentric outer annular clearanceof which the latter communicates with said fluid conduit for receivingfluid from the same; and partition means closing the upstream end ofsaid inner clearance against entry of fluid from said fluid conduit sothat fluid can enter said inner annular clearance only by passing intosaid outer annular clearance and thereupon through said sieve insert.

2. A glow plug as defined in claim 1, wherein said annular sieve insertprojects axially beyond said free end of said glow pin.

3. A glow plug as defined in claim 1, said partition means being a ringmember engaging the upstream end portion of said annular sieve insert.

4. A glow plug as defined in claim 3, wherein said ring member is ofsubstantially U-shaped cross-section and embraces said upstream endportion of said annular sieve insert.

5. A glow plug, particularly for use in diesel engines, comprising incombination, a housing provided with an internal passage having a frontend and being bounded by an inner circumferential surface; an elongatedglow pin received in said passage rigid with said housing and usefulapplication in other types of constructions differing from the typesdescribed above.

While the invention has been illustrated and described as embodied in aglow plug particularly suited for use in diesel engines, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting features thatfrom the standpoint of prior art fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. A glow plug, particularly for use in diesel engines, comprising incombination, a housing provided with an defining with said innercircumferential surface an annular fluid conduit through which fluid mayflow in direction towards said front end, said fiow pin having a freeend located adjacent said front end of said passage; an annular sieveinsert mounted in said conduit concentrically surrounding said flow pinin the region of said free end thereof with spacing from said glow pinand said inner circumferential surface and defining with the two aninner and a concentric outer annular clearance, said sieve insert havinga downstream end portion located proximal to said front end of saidpassage; and connecting means rigidly connecting said downstream endportion of said sieve insert with said housing in the region of saidfront end of said passage.

6. A glow plug as defined in claim 5, said connecting means extendingtransversely of said outer annular clearance and fastening and centeringthe sieve insert in said housing.

References Cited UNITED STATES PATENTS 2,966,942 l/1961 Breese et al.431-263 X 2,966,943 1/1961 Breese 431--263 X 3,353,520 11/1967 Haag123l79 X 3,407,794 10/ 196 8 Nagai et al 3l798 X EDWARD G. FAVO'RS,Primary Examiner US. Cl. X.R. 123l79; 3l798

